via SMS or IVR call is also used by a majority of companies, wherein the user has to enter the received to confirm the identity. User being asked to dial a number or a send a message which helps the server identify that the number is genuine and valid. With the advent of smartphones, type 0 or type 1 SMS are also being employed to send the codes which are used to verify the genuine user. Soft tokens generated within the smartphone or push messages can also be used. References External links Global Phone Format Validation Telephony